Feed control for sewing mechanism



y 1940. c. J. DAVIES ET AL 07,973

FEED CONTROL FOR SEWING MECHANISM Fifed March 7, 1958 6 Sheets-Sheet 1 FIG.6

' I CLARENCE J. DAVIES HAROLD M. RATLEY ATTORNEYS NVENTOR'.

July 16, 194-0. c. J. DAVIES ETAL 2,207,973

FEED CONTROL FOR SEWING MECHANISM Filed March 7, 1938 6 Sheets-Sheet 2 4| g 0 o 2 ll o o f g 44 24 II 3 44 0 b 43 :00 l 42 33 I2 I 2] 6a 0 I52 32 I3! 22 f 3| 0 7 3o 36 U H p 63 0 \I\\/;:/

/g 1 I33 1: 0 I34 INVENTOR CLARENCE J. DAVIES HAROLD M. RAILEY ATTORNEYS July 16, 1940. c. J. DAVIES El AL 7 2,207,973

CONTROL FOR SEWING MECHANISM Filed March 7, 1958 6 Sheets-Sheet 4 0) w 0 l 2 Ll. 2

N 0-.- 1- N r 1 o 3 l0 '3 N LL g o g: o

V o g o O O E O o INVENTOR CLARENCE J. DAVIES HAROLD M. RATLEY A TTORNEYS y 1940. c. J. DAVIES ET AL 07,973

FEED CONTROL FOR SEWING MECHANISM Filed March '7, 1958 6 Sheets-Sheet 5 \IBO FIG]

ATTORNEYS Patented July 16, 1940 UNITED j STATES PATENT OFFICE FEED CONTROL FOR SEWING lWECHANISM Delaware Application March '7, 1938, Serial No. 194,460

3 Claims.

This invention relates toa method and apparatus for controlling the feeding of articles to a sewing machine.

In sewing machines of the type disclosed herein it is necessary to have a definitely predetermined relatipn between the sewing speed of the mechanism and the rate at which articles being sewed are fed during the sewing operation. The sewing machine forming the subject matter of the present invention is intended in one of its applications to sew door panels which are formed from relatively stiff board material. For this reason it is necessary to provide a so-called walking attachment to the sewing head so that the needles will move in the direction of feed while the needles are engaged with the panels. It will be obvious that if there is any substantial difierence between the controlled movement of the needles and the rate of speed of feed, there is a possibility of breaking the needles or otherwise damaging the mechanism.

The door panels, which are to be provided with a plurality of parallel seams by the sewing machine disclosed herein, are of generally rectangular shape but each door panel has extending therefrom a pair of ears or horns. This necessitates the door panels being positioned on the conveyor with a substantial space between adjacent door panels at the central portion thereof. Moreover, it is desirable to position the panels on a conveyor with a slight separation between adjacent panels.

The sewing machine disclosed herein is further adapted to sew seams which are of less extent than the cross section of the door panels. Suitable mechanism is provided for retaining the sewing needles disengaged from the panel until a predetermined portion of the panel has been fed past the needles. At this time the needles are lowered into operative sewing position and sew a plurality of seams for a predetermined distance whichdistance is such that the needles are disengaged from the panels before the panels have been fed completely past the needles.

Due to the combination of circumstances just indicated, it will be apparent that the sewing needles are disengaged from the panels for a substantial interval .between adjacent panels. Since as before stated, it is necessary to provide for a relatively slow feed of the panels in timed relation to the sewing operation while the needles are engaged in sewing the panels, it will be apparent that a substantial saving in time ,4 may be obtained by increasing the rate of feed walking during the interval in which the needles are disengaged irom the sewing panels.

Accordingly it is an object of the present invention to feed a succession of panels past a sewing mechanism at differential speeds.

It is a further object of the invention to feed a succession of panels toward a sewing mechanism at a substantial rate of speed and to reduce the speed just prior to engagement of the needles with the panels.

It is afurther object of the invention to feed a succession of panels pasta sewing mechanism at a speed definitely related to the sewing speed of the sewing mechanism while the sewing operation is taking place and to substantially increase the speed of feed of said'panels during intervals when no sewing operation is taking place.

It is a further object of the invention to provide a sewing mechanism and a conveyor for feeding panels past said sewing mechanism in operative relation thereto in combination with automatically controlled means for increasing the speed of travel of said conveyors while the sewing needles are not engaged in the sewing operation.

It is a further object of the invention to provide a sewing machine, a conveyor and automatic means controlled by an article on the conveyor for elevating the sewing needles to inoperative sewing position and to lower the sewing needles into operative position so as to sew It is a further object of the invention to pro- I vide a two-speed feed for a conveyor with control mechanism for said two-speed feed, operated by an article on the conveyor.

It is a further object ofthe invention to provide two-speed feed mechanism for a conveyor, an electrically operated control means for said mechanism, and a switch actuating said control mechanism and positioned in the path of an article on said conveyor.

Other objects of the invention will be apparent as the description proceeds and when taken in conjunction with the accompanying drawings, wherein Fig. 1 is a broken side elevational view of a machine embodying the invention;

Fig. 2 is a broken longitudinal sectional View;

Fig. 3 is a side elevation of the two-speed con veyor feed control mechanism with parts in section;

Fig. 4 is a section on the line 4 of Fig. 3;

Fig. 5 is a plan view of a clutch element included in the speed control mechanism;

Fig. 6 is a section on the line 63 of Fig. 5;

Fig. '7 is a wiring diagram showing the circuit for the electro-magnetic clutch;

Fig. 8 is a diagram indicating the relationship between the adjacent panels on the conveyor;

Fig. 9 is a diagram indicating the relationship between the switches controlling the conveyor speed, the panels and sewing units;

Fig. 10 is a fragmentary elevational view, partly in section, showing a portion of the sewing mechanism in sewing position;

Fig. 11 is a View similar to Fig. 12, but showing the mechanism in collapsed position, wherein the needle bar is disconnected from driving engagement with the operating plunger; and

Fig. 12 is a fragmentary sectional view of the roller-wedge mechanism for locking the needle bar in retracted position.

As indicated in Figs. 1 and 2, the sewing machine comprises a main frame It provided with vertical standards H and cross bars' 52. In order to feed the panels to the sewing mechanism, a chain conveyor is provided which includes a frame portion M, idle sprockets l5, a chain l5 and a driving sprocket H. The chains l6 are received within guide channels 23, the channels 23 being of reduced height adjacent the sewing machine so that panels placed on the channels and fed toward the machine will be engaged by the chains at their forward ends. Suitable positive panel gripping means such for example as pins carried by the chains may be provided to feed the panels positively through the sewing mechanism. A second conveyor 18 is carried by the frame portion I9 at the opposite side of the sewing machine and is adapted to receive the panels as they are fed past the sewing mechanism. The conveyor E8 is carried by suitable rollers le and is positively driven by a sprocket 20.

Sewing mechanism, best seen in Fig. 2, comprises sewing heads 2|, which carry sewing needles 22. The sewing heads are supported at their lower end on a shaft 38 which is mounted in a bracket 35 secured to the cross bar l2. Each head is provided with a rocking guide member 32 in which is slidably mounted a needle bar 33 having one or more vertically adjustable sewing needles 22. The sewing needle is adapted to pierce the trim panel H and cooperate with an oscillating looper needle 35 disposed beneath the bed plate to form a stitch in the well known manner. A presser foot 36 is slidably mounted in the bracket 3i and is provided with a spring 36 to enable it to compress the fabrics passed beneath the reciprocating sewing needle. The needle bar 33 is reciprocated by means of an eccentric 3'! on the shaft 23 and. the eccentric also causes a slight rocking movement about the shaft 35) which provides the walking movement referred to. As shown in Fig. 2, the eccentric is surrounded by a yoke 31 to which is connected a rod 31 To the upper end of the needle bar 33 is adjustably connected a plunger 33 by means of a clamp 33 Releasable driving connections between the members 33* and the rods 3?? are provided by the coupler 26. The construction of the coupler 24'. is such that upon mechanical movement of plurality of apertures for the balls 33 the sewing heads upwardly, the driving connection between the rod 31 and the rod 33 is broken, and the sewing heads are retained in elevated position out of engagement with the work.

Releasable driving connections between the members 33 and 37* are provided by the coupler 24. As shown in Figs. 10 and 11, the plunger 33 is provided with an annular groove 33 into which may be thrust balls 33 A cylinder like member 38 is provided at its lower end with a shoulder 38 adapted to engage the enlarged piston like head 33 and limit its downward travel. The member 38 is threaded to the socket 31 at its upper end and its lower end is provided with a The lower end of the member 33 is provided with two vertically spaced annular grooves 38 which are adapted to be engaged by a spring-pressed ball 38 provided in a hollow stud 35 A sleeve 39 provided at its upper end with a flange member Z t is slidably mounted on the member 38 and is urged upwardly thereon by means of a compression spring 39. Another sleeve member 40 provided with an internally tapered groove 4!] is slidably mounted on the member 38 and the sleeve member 39, and its downward travel on the member 39 is limited by a flange 40 The tapered groove enables the member 40 when moved to the position shown in Fig. 10, to force the balls 33 into engagement with the groove 33 so that the rods 33 and 3% are locked together. However, if the member 49 is moved upwardly on the member 38, the balls are free to move outwardly and the head 33 is free to reciprocate within the cylinder 38. The spring-pressed ball 38 is carried by the member it and serves to hold the member so yieldingly in either the looking or unlocking position. The member 39 and the spring 39 serve as impact members so that when it is desired to lock the coupler from the position shown in Fig. 11 to that shown in Fig. 10, it is merely necessary to depress the flange 24 which will urge the sleeve M downwardly to the lower notch 38 as soon as the groove 33 arrives at a position to receive the balls 33 On the other hand, to unlock the device, it is merely necessary to strike the lower end of the sleeve 40 to move it into its upper position where the balls will be free to move outwardly and unlock the device.

The coupler is moved from locked to unlocked position and back again by means of a yoke 4| which has upper arms M and lower arms 41 to engage flange 2 and the lower end. of the cylinder 0, respectively. The yoke is slidably mounted on an upright 42 which serves as a bear- 1- in Figs. 10-12. A cover like member 32 is.pr0

vided on the guide block 32 and is provided with a wedge-shaped slot 32* in which is mounted a roller Q55 provided with a head 45 A slide block 45 is yieldingly urged downwardly by a spring 46 against the roller 45 urging the latter to locking position. 1

The upper end of the cover member 32 is pivotally connected to the guide block 32, as indicated at 32, and its lower end is yieldingly held against the guide-block by means of a cap screw 32 provided with a compression spring 32 'so that the locking engagement is somewhat yielding. As shown in Fig. 12, the needle-bar is pro- 7 vided with a hard steelinsert 33 'to re'duce the amount of wear. In operation theneedle-bar'is drawn to its uppermost position by theshoulder 38 pulling up'the head 33. During this'movemerit, the roller 45 is urged downwardly by the block 46 and the bar is thereby locked in retracted position. This happens immediately after the driving mechanism has been disconnected by the coupler so that'the wedge device merely supports the needle-bar assembly.

The roller wedge device C -is operated by means of a pair of lever arms 5| which are pivotally mounted on guide block 32 by means of a pivot 5|. The front end of each lever is provided with a pair of notches 5 I 'which are adapted to be engaged alternately "by a spring-pressed plunger 52 so that the levers will rest in either locking. or unlocking position. The front upper edges of the levers 5| are adapted to'engage the heads 45 and unlock the needle-bar when the levers are rocked to the position shown in Fig. 10. Movement of the levers 5| is controlled by a rock shaft 53 which is journalled in the yoke 4| and has a pair of rearwardly extending arms 53 which are connected "to'the rear ends of the levers 5| by means of links 54. As best shown in Fig. 11, the rock shaft is further provided with forwardly extending arms 53 disposed between the yoke arms 4| and are adapted to engage the lower end of the member 38 of the rod 3'I when the yoke 4| is in proper position. The yoke 4| is further provided with laterally extending stop arms 4| which are adapted to engage the ends of the links 54and' rock thelevers 5| to the position in Fig. 10 when the yoke 4| is moved to its lowermost position. The stop arms 4I are fixed to the yoke 4| so that in the collapsed position illustrated in Fig. 11 therewill be about five thirty seconds'of an inch clearance between the top of the links 54 and said arms. -This clear-. ance is taken up during the fir'stdownward movement of the yoke as the links .54 are held in position through-the action of plungers52 onthe levers 5|. However, as the [yoke continues to move downwardly the links 54 are forced down and the levers 5| are pressed into the position shown in Fig. 10, causing the roller-wedge 45 to be raised to release the needle-bar. I

a A solenoid 62 is provided and through suitable mechanism (not shown) is adapted to rotate the shaft 43 through 180 upon actuation. The solenoid 62 is in an electric circuit controlled by a plurality of switches 63, 64, which are adjustably positioned in the path of the panels H as they arefed past the sewing-mechanism. The switches are positioned and connected so that after a predetermined. portion of the panel H has passed the sewing needles the solenoid 62 is operated to rotate theshaft 43 through 180 to lower the coupler 24- which will have the effect of lowering the needles 22 into operative position and to interlock the rods 33 and 31 so as to drive the sewing needles. At a predetermined point in the travel of the panel H past the sewing needles, switches 64 are released to again operate the solenoid 62 to rotate the shaft 43 through 180 to elevate the coupler 24 to dis connect the rods 33 and 31 and to :retain the needles 22 inele'vated inoperative position.

The arrangement just described is fully shown and claimed in application Ser.'No-. 123,538, of Allister I S. Mitchell, Clarence J. Davies and Harold M. Ratley, filed February 1, 1937, and has resulted in Patent No. 2,186,838. I

From the-foregoing brief description it will be apparent that the rate at which the sewing mechanism operates depends upon the rate of rotation of the shaft 23. A motor I00 is carried by the frame I0 and is adapted to drive a sprocket wheel I0| through the interconnection of a suitable chain I02. The sprocket wheel IOI is supported by a shaft I03 which also carries in rigid relation a pulley which drives a belt I04 operatively connected to a second pulley on the shaft 23. The vertical shaft I05 is supported by the frame and is driven through a bevel gear connection indicated at I06 from the shaft 23'. The shaft I 05 is adapted to rotate a shaft I 06 through bevel gears I01 and shaft I08 is also driven in timed relation to the shaft I05, I06, through the intermeshing engagement of the gear I09 carried by shaft I06 and the gear I|0 carried by shaft I08. Shafts I05 and I08 are adapted to operate parts of the sewing mechanism in timed relation to the reciprocation of the sewing needles as controlled by rotation of the shaft 23'. A pair of sprocket wheels I20 and I2| are keyed or otherwise rigidly secured to the shaft I05 and are adapted to rotate parts of the two speed feed control mechanism generally indicated at I22.in Fig. 1 and shown in detail in Figs. 3 and 4.

The conveyor feed is controlled by a shaft I23 which carries the sprocket wheel I'Iv previously referred to and in addition a second sprocket wheel I24 which drives the sprocket wheel 20 through the chain I25. The shaft I23 carries a worm gear I26 which meshes with a worm I21 carried by a shaft I30.

From the foregoing it will be apparent that the shaft 23' will be driven at a speed dependent upon the speed of rotation of the motor I00, and the shaft I30 will be driven at a speed dependent upon the relationship of the speed control mechanism I22. The feed roller |3| is driven by a chain I32 which engages a sprocket wheel on shaft I34. Shaft I34 also carries a second sprocket wheel I33 which is in operative engagement with a secondchain I35 which is driven from a sprocket wheel I36 keyed to shaft I23. Therefore the speed of the conveyors and the associated panel feeding means depends upon the speed of rotation of the shaft I23, and hence on the speed of rotation of shaft I30.

Referring more particularly to Figs. 3 and 4,

the shaft I05 has keyed or otherwise secured thereto sprockets I 20 and I2I. It will be noted that the sprocket I2I is of substantially larger diameter than the sprocket I20. Chain I40 operatively connects sprocket I2I and a second sprocket I4| which is rotatably mounted on shaft I30. A second chain I42 is driven by sprocket I20 and operatively engages a second sprocket I43 which is 'rotatably carried on shaft I30. Suitable adjustable idle sprockets I44 and. I45 are carried in slotted brackets I46 for the purpose of adjusting the tension of the chains I40 and Since the sprocket I2| is of larger diam eter'than the sprocket I20 and since the sprocket MI is of smaller diameter than the sprocket I43, it will be evident that sprockets MI and I43 are driven at substantially different speeds. It has been found that satisfactory results are obtained when the relationship between sprockets is such that sprocket MI is driven at substantiallytwice the speed of sprocket I43. The sprocket I43 is secured in non-rotatable relation to the housing I4'I-of a one-way clutch mechanism. This clutch housing is mounted for free rotation on the shaft I 30, suitable bushings I48 being provided therefor, and rests on a collar I49 which is keyed cated at I5I.

- bracket or otherwise secured to the shaft I30. the two-piece housing I41 is a one-way thrust ring I50 shown in detail. in Figs. 5 and 6. The thrust ring I50 is keyedto the shaft I30 as indi- The thrust ring I50, as best indicated in Fig. 5, has a plurality of peripheral recesses I52 shaped as shown in Fig. 5. Thrust ring I50 is received within the housing I41 in closely embraced relationship so that the recesses I52 form chambers provided at one end with an abrupt shoulder I53 and which chambers taper in the opposite direction. Received within the recesses thus formed are a plurality of cylindrical thrust rollers I54. The thrust rollers are freely retained within the chamber referred to and as will be apparent, rotation of the housing I41 in a counter-clockwise direction relative to ring I50, as seen in Fig. 5, will cause the thrust rollers to become wedged in the tapered ends of the recesses and thus to transmit the thrust between the housing and the thrust ring I 50.

From the foregoing it will be apparent that rotation of the shaft E05 results in a corresponding timed rotation of the shaft I30 through-the agency of the sprocket I20, chain I42, sprocket I43, housing 841, thrust rollers I54, thrust ring I56 and keys I5I.

At the same time the chain I40 is rotating the sprocket MI at a substantially higher speed than the rotation of the sprocket I43. The sprocket MI is rigidly secured to an annular member I60 which is mounted for free rotation on the shaft 530 and is supported by a collar I6I keyed to the shaft. Annular member I60 is bolted or otherwise secured to a flexible annular metal diaphragm I62 at the inner edge thereof. The outer edge of the diaphragm is bolted or otherwise secured to a magnetizable annular block I63 also carried by the shaft I30 for free rotation. It

' will be apparent that the flexible diaphragm I62 permits relative axial movement between block I63 and the annular member I60. A second block I64 which includes solenoid windings (not shown) is keyed to the shaft I30 as indicated at I65. The block I64 is provided at its outer periphery with friction material I66 which is adapted to engage the block I63 upon energization of the solenoid. The solenoid is connected to a pair of conducting rings I61 and I68 and a I69 carries a pair of spring pressed brushes I10 engaging the conductor rings I61 and I66 and a bracket I69 carries a pair of spring pressed brushes I10 engaging the conductor rings. The circuit to the solenoid is controlled by a set of switches which will be subsequently described.

It will be apparent from the construction just described that upon energization of the solenoid contained within the block I64 that the magnetizable block I63 will be drawn upwardly. This motion will be permitted due to the flexible diaphragm I62 and will not cause corresponding upward movement of the annular member I60 or the sprocket I4 I. Upward motion of the block I63 causes frictional engagement between the block and the friction material I66. Since the sprocket MI is driven at substantially higher speed than the shaft I30, the frictional engagement between the parts just mentioned will cause the block I64 to be brought up to the speed with the block I63 and through the key I65 the speed of rotation of the shaft I30 will be correspondingly increased. Due to the one-way action of the thrust mechanism which includes the housing I41, thrust rollers I54 and thrust ring I50, this increased speed of rotation of the Within the' shaft I30 is permitted without affecting the speed of rotation of the housing I41 and interconnected sprocket I43.

As-best seen in Fig. '1, the

wiring for the solenoid includes a transformer T connected to.

primary circuit P and a secondary circuit grounded at G. The other branch of the S60? ondary circuit includes a conductor IN, a solenoid winding I12, a conductor I13 which leads to a group of four'normally closed switches I14, I15, I16 and I11. 'These switches are arranged in parallel and are all grounded. From the foregoing it will be' apparent that when any one of the switches I14 to I11 are closed the circuit is completed through the solenoid I12. The solenoid I12 includes a plunger I which carries a pair of interconnected contacts I8I. The circuit for the speed control solenoid included in the block I64 includes a pair of spaced contacts I82 adapted to be bridged by contacts I8I. These contacts are normally open but are retained closed as long as any of the switches I14 to I11 are in closed position.

Since as previously described, the shaft I30 is driven at relatively slow speeds while the solenoid in block I64 is de-energized, it will be apparent that the arrangement just described provides a safety feature. Upon failure of the current either to the solenoid in block I64 or to the .relay solenoid I12, the solenoid in block I64 will be de-energized and the shaft I30 will be driven at a slower speed through the medium of the one-way clutch'mechanism I41.

As indicated in Fig. 9, the switches I14 to I11 are individually adjusted, being mounted on adjustable slide blocks I85.. For this purpose the blocks I85 are slidable in ways indicated at I86. The proper setting of the switches I=14 to I11 is indicated by the diagrams shown in Figs. 7 and 8. If it is desired to sew a plurality of parallel seams I81 on the panels H, these sams to commence at point I81 and to terminate at point I81", the switches'63 and 64 are adjusted so as to control the raising and lowering of the sewing heads at the proper time through mechanism previously referred to. The panels may beof any dimension, the critical dimensions which control the setting of the switches I14 to I11 being indicated by the letters A, B and C in Fig. 8. The distance A is the distance from the leading edge of a panel to the point on the panel where it is desired to commence the seam. The distance B is the distance from the termination of the seam to the trailing edge of the panel. The distance 0 is the distance from the trailing edge of one panel to the leading edge of the'next succeeding panel.

The switches I14 to I11 are adjusted along the ways I86, so as to be spaced apart the distances shown in Fig. '7. Switch I14 is separated from switch I11 by a distance equal to A'plus B, minus approximately two inches. The switches are set two inches closer together than the distance A plus B so as to permit the conveyor mechanism to slow down prior to actuation of the sewing mechanism and to allow a reasonable factor of safety. As seen in Fig. 7, the advancing panel I-I successively actuates switches I14, I15 and I16 to open the circuit. The opening of these .three switches has no effect on the relay solenoid I12, since the circuit is completed through this solenoid through anyone of the switches I14 to I11 which remain closed. Immediately upon opening of the switch I11, however, all of the switches I14 to I11 will be retained in open position by the circuit through the relay solenoid I12 which opens the switch controlling the speed control relay in the block I64 at the contacts I82. De,

energization of the solenoid in the block I64 permits the magnetizable block I63 to drop away from'the friction material I66, due to its weight and the resiliency of the annular diaphragm I62. At this time while the sprocket I4I continues to be driven at relatively high speed, the shaft I30 slows down until it is rotating at a somewhat lesser speed than the one-way clutch housing I41. Since the one-way clutch housing is at this time rotating slightly faster than the shaft I30, the thrust rollers I54 will be carrying toward the tapered edge of their recesses and will cause driving engagement between the clutch housing I41 and the shaft I30.

The switch I11 is accurately positioned, so that shortly after its actuation by the panel H the panels are in position for the actuation of the sewing needles to commence. The panel is advanced at sewing speed and the sewing continues until the trailing edge of thepanel H passes over the switch I 14 and permits the same to close. This again energizes relay solenoid I12 and as previously described, causes acceleration of the conveyor to its rapid feeding speed. Switches I14 and I11 are all that would be necessary to provide for slowing the conveyor down during the passage of a single panel. However, when, as contemplated, a succession of closely spaced panels is placed on the conveyor, it is necessary tov provide intermediate switches I15 and I16. These switches are spaced apart and are spaced from switches I14 and I11 respectively a distance somewhat less, as for example, one inch, than the dimension C shown in Fig. 8. Thus as the space between succeeding panels passes over the switches, each switch is permitted to close its circuit for a short interval of time and to remain closed until the next succeeding switch is permitted to close by the passage of said space. This will result in the panels being fed at slow sewing speed while the needles are engaged in sewing and for a small interval immediately before and after sewing and at a substantially increased speed for the major portion of the interval that the needles are inoperative.

As indicated in Fig. 8, the sewing mechanism will be operative for only about half the time, although this of course may vary with different dimensions of panels and diiferent lengths of seams. However, by increasing the feeding speed during the interval when no sewing is occurring, ti is possible to increase the output of a sewing machine of this nature by a substantial amount. We have illustrated our feed control in connection with a particular type of sewing mechanism. It will be appreciated, however, that it need not be so limited, and will be equally useful in feeding articles past any treating mechanism or treating station whereit is necessary to limit the speed of the articles as fed past said mechanism or station, and where a substantial interval exists between the adjacent articles or the portions of adjacent articles which are to be treated.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

What We claim as our invention is:

1. The method of forming seams in a plurality of articles fed past a sewing mechanism having needles normally in operative juxtaposition thereto which comprises placing said articles in series on a. conveyor, moving said conveyor at a definite speed to advance said articles toward said sewing mechanism, positioning the needles ofsaidsewingmechanism in inoperative position, while a portion of one of said articles passes said mechanism, reducing the speed of said conveyor, moving said needles into sewing position and forming seams, moving said needles to inoperative position and increasing the speed of said conveyor.

2.'Sewing apparatus for sewing seams along only the mid portion of articles, comprising a conveyor, a sewing mechanism having needles movable to and from article engaging position, a two speed drive for said conveyor, control means. for said conveyor comprising means actuated by an article on said conveyor to reduce the speed of said conveyor to a sewing speed after a predetermined portion of an article has passed said sewing mechanism, other means effective thereafter for moving said needles to sewing position, and for subsequently raising said needles to inoperative position before said article has passedsaid mechanism, said control means being effective thereafter to increase the speed of said conveyor, said means actuated by an article on the conveyor comprising a plurality of switches eifective to decrease conveyor speed when all are engaged by an article, and eifective to increase conveyor speed thereafter when one of said switches is released by an article.

3. Sewing apparatus for sewing seams along only the mid portion of articles, comprising a conveyor, a. sewing mechanism having needles movable to and from article engaging position, a two speed drivefor said conveyor, control means for said conveyor comprising means actuated by an article on said conveyor to reduce the speed of said conveyor to a sewing speed after a predetermined portion of an article has passed said sewing mechanism, other means efiective thereafter for moving said necdles to sewing position, and for subsequently raising said needles to inoperative position before said article has passed said mechanism, said control means being effective thereafter to increase the speed of said conveyor, said means actuated by an article on the conveyor comprising a plurality of more than two switches effective to decrease conveyor speed when all are engaged by an article, and effective to increase conveyor speed when one of saidswitches is not engaged, whereby conveyor speed -is shifted during the interval when no article is passing said mechanism even though the first and last of said switches are engaged by different articles.

CLARENCE J. DAVIES.

HAROLD M. RATLEY. 

